Zero radial play idler arm bracket bearing

ABSTRACT

An idler arm bracket bearing includes a plurality of inwardly extending fingers to contact the bracket. The fingers deflect toward the bearing body as the fingers contact the bracket, thereby ensuring a full contact fit that provides a tighter joint assembly. Rib members are located between the fingers to center the bracket and limit the resilient deflection of the fingers.

TECHNICAL FIELD

The present invention relates generally to socket joints, and moreparticularly to socket joints that permit rotation of brackets andstuds, but resist relative radial displacement and misalignment.

BACKGROUND OF THE INVENTION

Non-articulating joints are applicable to a wide range of applications,including Pitman-idler arms used in steering linkages of automotivevehicles. Exemplary joints are found in commonly-owned U.S. Pat. Nos.5,607,249, 6,146,045 and 6,371,682, to Maughan, the disclosures of whichare hereby incorporated by reference in their entirety. Such jointstypically include a cylindrical housing member adapted to receive abearing together with a portion of a stud or bracket. The bearingreduces the amount of friction between the housing and the bracket whilefrequently adapting for wear induced looseness between the stud andhousing members.

Such joints have critical manufacturing features. Typically, the studhead or bracket end must be precisely machined to ensure an adequatelytight joint. Further, the stud head or bracket end must be forced intothe bearing. Even with such tolerances, some bearings have anundesirable looseness after assembly, particularly when very rigid,stiff, inelastic materials are used. One way to tighten the joint is tolower manufacturing tolerances of the bearing, bracket, and socketassembly. However, some looseness may be experienced with lowertolerances, manufacturing costs may increase, and wear within the jointwill increase the looseness.

What is needed, therefore, is an improved idler arm socket joint thatforms a tighter assembly without requiring more costly manufacturingmethods.

SUMMARY OF THE INVENTION

The present invention overcomes the deficiencies of the prior art byproviding a bearing that affords a tighter assembly. In one exemplaryembodiment, the bearing for a non-oscillating joint includes a hollowfirst portion having a first diameter defined, at least in part, by afirst surface and a hollow second portion having a second diameterdefined, at least in part, by a second surface. The second diameter islarger than the first diameter. The bearing further includes a pluralityof finger members positioned on the first surface of the first portionso as to extend inwardly toward the axis.

In another exemplary embodiment, the non-articulating joint assemblyincludes a bearing having a body that includes a first end, a secondend, and a surface having a plurality of fingers extendingcircumferentially therefrom. The fingers are defined, at least in part,by a proximal end and a distal end, where the proximal end of eachfinger is closer to the body than a contacting surface of the distalend. The joint assembly further includes a bracket having a cylindricalend rotatably coupled to the bearing, where the fingers contact thecylindrical end.

In yet another exemplary embodiment, the bearing for a non-articulatingjoint assembly includes a body having a first end, a second end, and aninner surface having a plurality of fingers extending circumferentiallytherefrom, wherein said fingers are defined, at least in part, by aproximal end and a distal end, where the proximal end of the fingers iscloser to the body than a contacting surface of the distal end.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view an idler assembly in accordance with an embodimentof the present invention.

FIG. 2 is a partial sectional view of the idler assembly of FIG. 1,illustrating an embodiment of a non-articulating joint assemblyaccording to the present invention.

FIG. 3 is an enlarged side view of a portion of the bracket of FIG. 2

FIG. 4 is an enlarged bottom view of the bearing of FIG. 2.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, an idler assembly 10 is illustrated to include anidler arm 12 having a central body 14 interconnecting a stud assembly 18and a non-oscillating joint assembly 20.

Referring now to FIG. 2, an embodiment of the joint assembly 20 inaccordance with the present invention is illustrated to include agenerally metallic socket member 22 having a housing 24 with a firstbore 26 adjacent one axial end of socket member 22 and a second bore 28adjacent a second distal end of socket member 22. Joint assembly 20 isillustrated to further include a bearing 30 positioned within socketmember 22, a boot 32, a cover 34, a mating component, or bracket, 36partially positioned within bearing 30, and a spring 38.

With reference to FIGS. 2 and 3, the bracket 36 has a generally concavebracket mounting portion 40 that includes a number of openings 42 thatallow attachment of bracket 36 to a vehicle frame (not shown) usingconventional fastening techniques. A rotational end 48 of bracket 36 isdefined by a generally cylindrical end portion 50. End portion 50includes a bearing mating portion 54 that includes a first matingsurface 56, a second mating surface 58, and a tapered mating surface 60that extends between the first mating surface 56 and the second matingsurface 58. As illustrated, first mating surface 56 defines a largerdiameter about end portion 50 than the diameter defined by second matingsurface 58. A spring pocket 64 is formed in rotational end 48. Together,bearing 30 and bracket 36 are relative rotational components of jointassembly 20.

Spring 38 is preferably a conical telescopic compression spring andserves to maintain axial pre-load on bracket 36 and bearing 30, to beexplained in further detail below.

With reference to FIGS. 4 and 5, an exemplary embodiment of bearing 30is illustrated in greater detail. Bearing 30 includes a body 76 having acover end 80, a housing end 82, a first outer surface 84 with a firstouter diameter, a second outer surface 86 with a second outer diameter,and a transition outer surface 88 that extends radially between thefirst outer surface 84 and the second outer surface 86. A first innerdiameter 90 of bearing 30, adjacent first outer surface 84, has amultiplicity of ribs 92 formed thereon and extending radially inwardly.A second inner diameter 94 is adjacent second outer surface 86. Atransition inner surface 96 extends between the first inner diameter 90and the second inner diameter 94 and is generally adjacent transitionouter surface 88. Second inner diameter 94 has finger members 100 andrib members, or protrusions, 102 formed thereon and extending radiallyinwardly. First inner diameter 90 is defined, at least in part, by afirst surface 106. Second inner diameter 94 is defined, at least inpart, by a second surface 108.

As best seen in FIG. 4, finger members 100 include a finger body 110that extends from second inner diameter 94 having a pair of fingers 112extending radially inwardly and circumferentially with respect to theaxis A-A of bearing 30. Fingers 112 have a proximal end 116, a distalend 118, a contacting surface 122, a body surface 124, and a leewardsurface 128. The proximal end 116 is defined, in part, by the bodysurface 124. The distal end 118 is defined, at least in part, by thecontacting surface 122 and the leeward surface 128. As illustratedwithout a bracket inserted therein, the contacting surface 122 adjacentthe distal end 118 is closer to the axis A-A of bearing 30 than the bodysurface 124 adjacent the proximal end 116. As discussed below, fingermembers 100 contact the second mating surface 58 of bracket 36 toprovide a tight fit for joint assembly 20. As best seen in FIGS. 4 and5, the outline of fingers 112 taken normal to axis A-A is generally thesame along the axial length of fingers 112.

Finger body 110 provides a longitudinally extending attachment betweenfingers 112 and body 76 to allow the distal ends of fingers 112 todisplace radially as rotational end 48 of bracket 36 is positionedwithin bearing 30, as discussed below. Bearing 30 is preferably formedof Nylon® and even more preferably formed of Nylatron® GS, although anysuitable bearing material that may be resiliently biased may be used.

Referring again to FIG. 2, cover 34 is received in housing 24. Cover 34is sized to have an outer diameter that is substantially equal to thediameter of first bore 26. Cover 34 further includes a lubricationaperture 140 extending therethrough. Lubrication aperture 140 ispositioned substantially in the center of cover 34 and aligns withlubricant well 64. A more detailed discussion of conventional aspects ofthis embodiment, such as lubricant well 64, cover 34, and spring 38 canbe found in the above referenced U.S. Pat. No. 6,371,682. As describedbelow, the cylindrical bearing mating portion 54 is coupled to bearing30 for rotation therebetween. Bracket 36 rotates in a generallyconcentric arrangement within bearing 30. Any deviation from concentricalignment of bracket 36 and bearing 30, or oscillation, is reduced bythe interference fit between fingers 112 and second mating surface 58.

To assemble joint assembly 20, bearing 30 is fully inserted axially intohousing 24. The bracket mounting portion of bracket 36 is insertedthrough cover end 80 of bearing 30. Bracket 36 is inserted throughbearing 30 until tapered mating surface 60 contacts transition innersurface 96. As second mating surface 58 is inserted concentrically intosecond inner diameter 94 of bearing 30, fingers 112 contact secondmating surface 58 in an interference fit. This interference fit requiresless insertion force than is required to insert a bracket into manyconventional close tolerance bearings. The distal ends 118 of fingers112 displace radially, away from the axis A-A of bearing 30 and towardsecond inner diameter 94 of body 76. In this manner, fingers 112 areresiliently biased with at least a portion of contacting surface 122tangential to second mating surface 58 and at least a portion of finger112 adjacent contacting surface 122 in tension. This tension in aportion of each finger 112, coupled with other stresses experienced byfingers 112 and finger members 100, creates a force that retains bracket36 and bearing 30 in a concentric arrangement, thereby reducing anyrelative oscillation in joint assembly 20 during operation of idlerassembly 10.

As best seen in FIG. 4, protrusions 102 and ribs 92 center bracket 36 inbearing 30. Protrusions 102 also limit the deflection of fingers 112.Protrusions 102 and ribs 92 need not be as precisely machined as ribs ofother bearings that are intended to provide the only contacting surfacesbetween a bearing and a bracket. The flexibility of fingers 112 allowbearing 30 to be machined with a wider tolerance than conventionalbearings. In this manner, bearing 30 provides a tighter fit for jointassembly 20 while alleviating the need to machine bearing 30 to atighter tolerance. As bearing 30 wears due to contact with bracket 36,fingers 112 are kept in a tight-fitting contact with second matingsurface 58 due to the bias induced when bracket 36 was inserted intobearing 30.

As best seen in FIG. 2, spring 38 is positioned adjacent the rotationalend 48 of the bracket 36 and the cover 34 is positioned within firstbore 26 and adjacent the rotational end 48, resiliently biasing spring38. As illustrated, a portion of socket member 22 is mechanicallydistorted to retain cover 34 in a desired position.

Transition inner surface 96 and tapered mating surface 60 interact inpart to prevent relative axial movement between bearing 30 and bracket36. For applications where relative axial movement is desired, or of noimport, transition inner surface 96 and tapered mating surface 60 can beeliminated to provide a further embodiment of the joint assembly of thepresent invention.

While the invention has been described with respect to specific examplesincluding preferred modes of carrying out the invention, those skilledin the art will appreciate that there are numerous variations andpermutations of the above described systems and techniques that fallwithin the spirit and scope of the invention as set forth in theappended claims. For example, fingers 112 and protrusions 102 may extendfrom bracket 36 and bearing 30 may define a cylindrical mating surfacethat contacts fingers 112.

1. A bearing for a non-oscillating joint extending along a central longitudinal axis of rotation, comprising: a first portion defined by a first diameter and a first surface; a second portion defined by a second diameter and a second surface; a plurality of radially displaceable finger members extending radially inward toward said axis from said second surface of said second portion; and a plurality of rib members extending radially inward toward said axis from said second surface; wherein the first diameter is different from the second diameter; wherein the first portion is axially offset from the second portion.
 2. The bearing of claim 1 further including a plurality of ribs extending radially inward toward said axis from said first surface.
 3. The bearing of claim 1 wherein said rib members are interposed between at least a portion of said finger members.
 4. The bearing of claim 1 wherein said finger members extend circumferentially with respect to said axis.
 5. The bearing of claim 4 wherein the cross section of said circumferential extension of said first portion and said finger members normal to said axis is defined by a generally consistent outline relative said axis.
 6. The bearing of claim 1 wherein said finger members are selectively adapted to be resiliently biased away from said axis.
 7. The bearing of claim 1 wherein each of said finger members are defined, at least in part, by: proximal end, a distal end, a contacting surface, a body surface, and a leeward surface, wherein said distal end is defined by the contacting surface and the leeward surface, wherein the contacting surface is radially closer to said axis than said leeward surface, wherein the proximal end is defined by the contacting surface.
 8. The bearing of claim 1, wherein said first and second portions are defined by a body, wherein the body is hollow, wherein the hollow body is defined by the first surface and the second surface, wherein the first surface and the second surface define, respectfully, the first diameter and the second diameter.
 9. The bearing of claim 8, wherein said first diameter is larger than said second diameter.
 10. A bearing for a non-oscillating joint extending along a central longitudinal axis of rotation, comprising: a first portion defined by a first inner surface; a second portion defined by a second inner surface; and a plurality of finger members extending radially inward toward said axis from said second inner surface of said second portion, wherein said fingers are defined, at least in part, by a proximal end, and a distal end; and a plurality of rib members extending radially inward toward said axis from said second inner surface; wherein the first inner surface is axially offset from the second inner surface.
 11. The bearing of claim 10, which each of said finger members is further defined to include: a body surface, a contacting surface, and a leeward surface.
 12. The bearing of claim 11, wherein the proximal end is defined by the contacting surface, wherein said distal end is defined by the contacting surface and the leeward surface, wherein the contacting surface is radially closer to said axis than said leeward surface.
 13. The bearing of claim 10 further including a plurality of ribs extending radially inward toward said axis from said first inner surface.
 14. The bearing of claim 10, wherein said rib members are interposed between at least a portion of said finger members.
 15. The bearing of claim 10, wherein said finger members extend circumferentially with respect to said axis.
 16. The bearing of claim 15, wherein the cross section of said circumferential extension of said first portion and said finger members normal to said axis is defined by a generally consistent outline relative said axis.
 17. The bearing of claim 10, wherein said finger members are selectively adapted to be resiliently biased away from said axis.
 18. The bearing of claim 10, wherein said first and second portions are defined by a body, wherein the body is hollow, wherein the hollow body is defined by the first inner surface and the second inner surface, wherein the first inner surface and the second inner surface define, respectfully, a first diameter and a second diameter.
 19. The bearing of claim 18, wherein said first diameter is larger than said second diameter.
 20. A bearing for a non-oscillating joint extending along a central longitudinal axis of rotation that retains a mating component, comprising: means for resiliently biasing a plurality of fingers of said bearing upon inserting said mating component into said bearing; and means for radially displacing the plurality of fingers of said bearing upon inserting said mating component into said bearing, wherein said bearing includes an inner surface having a first inner surface defined by a first diameter and a second inner surface defined by a second diameter, wherein the first diameter is greater than the second diameter, wherein the first inner surface is axially offset from the second inner surface; and wherein at least one of the inner surfaces of the bearing having ribs or protrusions.
 21. The bearing of claim 20, wherein the means for resiliently biasing the plurality of fingers includes a contacting surface of said plurality of fingers.
 22. The bearing of claim 21, wherein the means for radially displacing the plurality of fingers includes a distal end, wherein the distal end is defined by said contact surface and a leeward surface.
 23. The bearing of claim 20, wherein said plurality of fingers are circumferentially disposed on and extend from said inner surface of said bearing, wherein said plurality of fingers extend radially inwardly toward said axis, wherein said inner surface defines a passage formed in said bearing for permitting insertion of said mating component.
 24. The bearing of claim 20, wherein the plurality of fingers are formed on said second inner surface. 